This invention relates to the manufacture of semiconductor devices, and more particularly to an insulating film forming method for semiconductor device interconnection which is suitable for manufacture of highly integrated devices of multilevel interconnection structure, and to an apparatus for carrying out the method.
With the recent trend toward semiconductor devices of higher integration and higher density, the roughness of surface shape of the semiconductor devices has become greater, and reliable formation of a number of layers for interconnection on such a surface has come to be required. It is therefore necessary to form an insulating film for insulating the interconnection layers from each other, independently of the rough shape of the underlying surface and in such a manner that the insulating film will have a planar surface. For planarization of the insulating film, the methods under investigation at present are disclosed in Denki Kagaku (published by the Electrochemical Society of Japan) Vol. 57, No. 4 (1989), pp. 281-285, and Semicon NEWS 1989, June, pp. 49-67.
Many planarization methods which employ sputter-etching, etchback, reflow or the like have been proposed and studied.
For the formation of insulating films between interconnections for a semiconductor device, it is necessary not only to form a planar film but also to avoid influences of the film forming process on the device characteristics, to prevent the formation of voids in the film, to suppress dust generation attendant on the process, and so on. For higher productivity, in addition, the film forming process should not involve a wet treatment, such as use of a coating film, and should enable continuous processing in vacuum.
The above-mentioned prior arts have the following drawbacks. The method which uses sputter-etching and enables continuous processing in vacuum has the problems of influencing the device characteristics and generating dust. The methods using a coating film or etching are disadvantageous in that they use a combination of a wet process and a vacuum process. None of the conventional insulating film forming methods for semiconductor device interconnection satisfies the above-mentioned performance requirements for mass-production.
A general description of the conventional insulating film formation techniques is found, for example, in Semiconductor World, 1989, November, pp. 78-83.